Grant 4 Report post Posted February 1, 2004 Hello My E30 325i is a Japanese import, and therefore has a cat. The O2 sensor plugs straight into the cat. My question is....if I change the exhaust, and remove the cat, where would the o2 sensor need to plug into? I don't want to muck upthe ECU and the info it needs to do its magic. Cheers Quote Share this post Link to post Share on other sites
tHrEEtWoFiVe 0 Report post Posted February 1, 2004 (edited) My past experiences with o2 sensor is disconect it and tie it up out of the way. Reason being it has marginal effect on running quality and we didnt have emission testing requirements to meet. If you choose to do this you will however need to find out whether you should leave it open circuit or closed circuit. HOWEVER, Im not sure as to what the requirements are for emission testing here any more and if they do monitor it you will require it connected as your car will run rich with it disconnected, (generally). To give you a example on all my past cars. I have disconnected the item, removed the cat and never looked back. The adjustments to fuel ratio are small, from memory. Imagine on a scale of 1-100. This being the fuel ratio variance that the ecu controls. The oxy sensor input makes up 1-3 of that input (Possibly even less). All that happins with it disconnected is it will move to one end of the scale that it works in, i.e say 3. Which would possibly give you a slightly rich mix at idle. If you were in a country like the US you would fail badly on emission testing for this. As you car is pumping out emissions. If anyone has a more enlightened view by al means fire away, as Im a bit rusty on this side of things. Edited February 1, 2004 by tHrEEtWoFiVe Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 1, 2004 Cheers, I might unplug it, go for a reasonable drive and see how it runs. Quote Share this post Link to post Share on other sites
gmccormack 0 Report post Posted February 1, 2004 Grant the sensor in the cat is not the O2 sensor , it is a temp sensor that warns you the cat is over heating .The O2 sensor IF FITTED is on the pipe straight after the manifold . Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 1, 2004 Ahhhh...thanks Graeme, that would make sense. That sensor is faulty, and I have removed the light from the overhead panel. Therefore it is safe to assume I can remove the cat (and the sensor too???). Cheers Quote Share this post Link to post Share on other sites
bumpstop325 0 Report post Posted February 2, 2004 the sooner the better. and the more happier Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 3, 2004 I am thinking of just getting the cat cut out, and then pipes welded in to fill the gaps....is this something that an exhaust shop would do? I just feel that at the age the car is, the cat must be restricting the exhaust flow somewhat. Cheers Quote Share this post Link to post Share on other sites
Napier_E36 0 Report post Posted February 14, 2004 Oh very much so grant - open that exhaust up and let her breathe!!!!! lol I had the exhaust done on my 325 from the headers back with a single 2.5inch pipe - never looking back - they cut the cats out, and with the sensor inside the cat they cut a hole in the resonator with a gas axe and welded it in to the side of it. No worries... that way if it was required it isnt going to matter too much! Quote Share this post Link to post Share on other sites
Gus 5 Report post Posted February 14, 2004 heard grants exhaust today for the first time.....sooooo nice...cant wait to get the exhaust i have in my shed on! Quote Share this post Link to post Share on other sites
Napier_E36 0 Report post Posted February 14, 2004 sweet - what have you done grant? just knocked the cats out? or have you done a full system? Did you keep your cats? Ive heard a nasty rumour that they are going to bring emission standards in as part of the Keyoto(spelling?) Agreement. The Keyoto Agreement (for those who dont know - Im one of those people, but Ill tell you what I know, and if Im wrong I hope someone can correct me!) is like a treaty signed by a group of countries in the Pacific, and basically its like a contract saying that each country will take steps to help make their countries cleaner and greener etc. Part of that is to bring emission level standards, and that means having Catalytic Convertors in cars. Japan is part of that agreement, and that is why all cars that come from Japan have to have cats. It sucks that this is the case - you gain extra power by removing the cats, less restriction = more power. (you would have noticed this wouldnt you Grant?) However, having said this, I have also been told that Vehicles already in the country wont have to worry about installing a cat, just vehicles imported after a certain date. Pretty similar to how the government bought in the new frontal impact standards, where vehicles must conform to a certain crash test standard before they can get a compliance thru the LTSA. Im sorry if I have details wrong here - this is just how I have understood what was told to me. Cheers Blair Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 15, 2004 no, cat still in there, and still standard exhaust...just has a good throaty note to it, and screams at high revs. The cat is starting to stink a bit though, so it is closed to poked, so will get it removed reasonably soon. Cheers Quote Share this post Link to post Share on other sites
Napier_E36 0 Report post Posted February 15, 2004 no, cat still in there, and still standard exhaust...just has a good throaty note to it, and screams at high revs. The cat is starting to stink a bit though, so it is closed to poked, so will get it removed reasonably soon. Cheers ive heard that if you take the cat out and smash all the ceramic out then put it back in, it is just as good as cutting it out all together. however it is probably easier to take that out and replace it with a straight pipe. either way not cats gives more power and a nice sound!!! how has it changed? the way gus sounds, it sounds like youve done something to it and made it go better, or is it just the same as always? Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 15, 2004 Nothing has changed, I am just used to it. People keep telling me it has a good sound. Yeah, will get the cat cut out and straight pipe(s) welded in to replace it. Cheers Quote Share this post Link to post Share on other sites
Gus 5 Report post Posted February 15, 2004 yeah no its just a stock 325 exhuast.....so good....cant wait to get mine on.....grant have u seen my 325 exhaust? its a lot bigger than most i have seen....gonna sound sooo nice....kinda need to do it now..esp after being pulled over last nite.... Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 15, 2004 Gus What were you pulled over for? The exhaust noise? Cheers Quote Share this post Link to post Share on other sites
Gus 5 Report post Posted February 15, 2004 yeah....they were training up a new guy...thought that i was an easy target to do practice on....my car was pink stickered last sept before i got it......dick of a last owner....so yeah.....looking very forward to getting my exhaust sorted out.....sick of milo can noise..... Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 15, 2004 Hope you didn't get a ticket. I have asked for a couple of quotes this morning to get my cat removed, and straight pipes put in instead. If the cost isn't too bad, I will get this removed before the driver training day. Cheers Quote Share this post Link to post Share on other sites
Napier_E36 0 Report post Posted February 15, 2004 If the cost isn't too bad, I will get this removed before the driver training day. from memory - cutting out cats and putting in straight pipes is about $40 - 50 per cat - most cars have only one - but my bimmer had 4 - 2 on each pipe, but that didnt matter - i was putting in whole new pipe too. But it shouldnt be all too bad grant - will make a big difference (should do anyway!) Quote Share this post Link to post Share on other sites
Grant 4 Report post Posted February 15, 2004 I am pretty sure in my E30 I only have the one cat. If that is all it costs, I will definately get it done. Should make it breathe a bit easier (well exhale anyway). It looks like it can be unbolted, removed and then just replaced with two bits of straight pipe welded in place. Looks as though it should be easy. Cheers Quote Share this post Link to post Share on other sites
